Fedora 22 and 23 already ship GnuPG 2.1, which merged the private keyring into the public keyring. Enigmail interfaces GnuPG 2, so keys created with Enigmail and GnuPG 2.1 are stored in the public keyring file.
Use gpg2
instead of gpg
if you can; otherwise you'll have to export the secret keys from gpg2
and import it to GnuPG 1 again:
gpg2 --export-secret-keys [key-id] | gpg --import